Once rechargeable battery voltage reaches a minimum threshold voltage, further discharge of rechargeable batteries will result in irreversible chemical changes in a rechargeable battery, destroying a rechargeable battery's ability to recharge, necessitating battery replacement. As rechargeable batteries are typically expensive and, in some devices, awkward to replace, devices that contain rechargeable batteries may contain battery protection circuitry to disable further discharge when the minimum threshold voltage is attained. In these devices, the shutdown voltage is set to the minimum threshold voltage. Thus, reaching the minimum threshold voltage results in the device shutting down to prevent damage to the battery, regardless of the state of the device.
While some devices will shutdown prior to reaching the minimum threshold voltage, for example, due to an inactivity timeout, to save power or to preserve an energy buffer, shutdown still results when the battery reaches the minimum threshold voltage, in order to avoid permanent battery damage.